Negative resistance



Dec. 6, 1938..

E. H. YONKERS, JR

NEGATIVE RESISTANCE 3 Sheets-She et l Filed Aug. 26, 1936 Dec. 6,1938. 5YONKEFRS' JR 2,138,896

NEGATIVE RES I STANCE Filed Aug. 26, 1936 3 Sheets-Sheet 2 Dec. 6, 1938.E. H. YONKERS/JR 2,133,896

NEGATIVE RESISTANCE Filed Aug 26, 1956 3 Sheets-Sheet 3 vmawvvymm l9AMMA 3i? BY.

l-llllll ulll lllllllllllllll Patented Dec. 6, 1938 UNITED STATES PATENTOFFICE 13 Claims.

My invention relates broadly to negative resistance and moreparticularly to an improved circuit arrangement for producing negativeresistance.

One of the objects of my invention is to provide a circuit arrangementfor producing negative resistance by which the value of the negativeresist- .ance may be adjusted or controlled over a relatively wide rangewithin the same tube.

Another object of my invention is to provide a negative resistance whichmay be employed in the generation and amplification of alternatingcurrents, functioning with substantial stability over an adjustable orcontrollable range of values of negative resistance.

Still another object of my invention is to provide a method of producingnegative resistance for permitting adjustment and control of thenegative resistance over a wide working range.

A further object of my invention is to provide a construction ofnegative resistance device including a negative resistance elementformed by a multiplicity of alternately arranged plate members disposedbetween an electron emitting cathode and an anode and connected in anelectrical circuit having means for applying a difference of potentialacross the sets of alternately arranged plate members.

A still further object of my invention is to provide a negativeresistance device including an electron emitting cathode and an anodeand a negative resistance element disposed therebetween in an evacuatedvessel and electrically connected in a negative resistance circuitwherein both accelerating potential and bias potential applied to thenegative resistance elementare varied to give a predetermined dynamiccharacteristic for the device.

Other and further objects of my invention reside in the method ofproducing negative resistance, structural arrangement and circuitarrangement for the negative resistance device as set forth more fullyin the specification hereinafter following by reference to theaccompanying drawings in which:

Figure 1 is a vertical sectional view of the negative resistance deviceof my invention; Fig. 2 is a vertical sectional view taken through thenegative resistance device of my invention in a position revolved 180degrees with respect to the position on which the view of Fig. 1 istaken with the plate members constituting the negative resistanceelement shown in side elevation; Fig. 3 is a horizontal sectional viewtaken through the negative resistance device of Fig. 1 on line 33 ofFig. 1;

I Fig. 4 is a horizontal sectional view taken through the negativeresistance device on line 4-4 of Fig. 1; Fig. 5 is a plan view showingthe construction of one of the plate members of the negative resistanceelement employed in the negative resistance device; Figs. 6. and 7 aretheoretical views show- 5 ing the path of movement of electrons from thecathode to the anode and the blocking effect of the plate membersconstituting the negative resistance element, under difierent conditionsof operation of the negative resistance device; Fig. 8 10 is a schematiccircuit arrangement of the nega tive resistance device of my invention,employed as a means for generating alternating current where frequencystability is required; Fig. 9 is a schematic circuit arrangement of thenegative resistance device employed as a means for generatingalternatingcurrent where maximum power output is required or Where extreme lowvalues of negative resistance are required; and Fig. 10

illustrates a family of curves showing the variation in negativeresistance which may be obtained with a single tube.

The present invention is directed to improved means for producingnegative resistance. In my prior U. S. Patent 2,002,238, granted May 21,1935, for Negative resistance, I have shown means for producing anegative resistance characteristic wherein the desired inverse currentcharacteristic is obtained through the action of an electrode ofpeculiar, form upon a constant current electron stream. The value of thenegative resistance in this prior device depended largely upon the formor shape of the negative resistance element. In the present invention Iemploy a modified form of this element which permits convenient controlof the value of negative resistance obtained without altering thestructure of the device, in other Words, my prior patent discloses meansfor producing negative resistance of a relatively fixed value for agiven tube, whereas in the present invention I provide means foradjusting or controlling values of the negative resistance over a widerange within the same tube.

This feature increases the utility of the device and permits greaterconvenience and efficiency in the numerous services to which it may beapplied, such as the generation or amplification of alternatingcurrents. A further purpose of my present invention is to provide anegative resistance 5() device capable of delivering relatively largeamounts of power in the form of alternating current.

Referring more particularly to Fig. 1, I have shown a highly evacuatedenvelope I which may be of glass or other suitable material formed withthe inwardly directed axially aligned pedestal 2 which serves as asupporting means for the electrodes and lead-in wires hereafterdescribed. Extending through and supported by the pedestal 2 I providethe filamentary cathode 3 whose leadin conductors 4 and 5 are connectedso as to sup:- ply current for heating the cathode 3 to incandescence.Any suitable means may be employed as a cathode capable of producing aconstant current source of electrons. By the expression, constantcurrent source of electrons, I mean a source which delivers asubstantially constant electronic current regardless of the differenceof potential applied between the source and the other elements of thedevice over a working range. The filamentary cathode 3 is maintainedtaut by a suitable spring device 30. introduced between the supportingmeans and the filament. Regardless of the expansion or contraction ofthe filamentary cathode 3, the cathode always remains stretched inspaced relation to the associated parts of the device. In the structuralembodiment shown in Fig. 1, I provide a negative resistance element 6consisting of a system of thin annular plates spaced from one anotherand positioned so that their axes are all coincident with thefilamentary cathode 3. The said annular plates are divided into twogroups, one group, 6c being rigidly attached to the support rod 8 andthe other, 62; to support rod 9. Said support rods are extended throughthe pedestal 2 and. connected to the terminal conductors l0 and H sothat external connection may be made separately to each of the twogroups of interleaved annular plates which in combination form thenegative resistance electrode. I also provide the cylindrical anode l2positioned so that it surrounds the previously mentioned elements, withits axis also coincident with the filamentary cathode 3. It is supportedfrom the pedestal 2 by the support rods l3 and I4 with the lead-in wire15 connected to support wire l3 so that the necessary electricalconnection may be made to the anode l2.

In the operation of the device the cathode 3 is heated to incandescenceby means of a battery or other current source which is connected to thelead-in wires 4 and 5. The anode I2 is c0nnect ed to a source ofpositive potential with respect to the cathode so that those electronswhich pass between the plates of the negative resistance element arereadily carried away.

The negative resistance element, that is the two sets of interleavedannular plates, Ba, and 6b, is, as a whole, operated at positivepotentials with respect to the cathode but one set of plates ismaintained at a higher potential than-the other set. The value of thisbiasing potential, that is, the potential difference between the twosets of plates, determines the operating range of as well as the slopeof the negative resistance characteristic. For example, referring toFig. 10 the curves A, B, C, D, E, F, and G represent the variation intotal current received by the negative resistance element 6 as thevoltage applied to it as a whole is varied and the curves formed by thebroken lines A, B, C, D, E, F, and G represent the corresponding changesin the anode current. The curves A and A result when there is nopotential difference between the two sets of annular plates. Curves Band B represent the characteristic of the device when the bias potentialis 10 volts, 0, C when the bias is 20 volts, and so on to F, F, whichresults whenthe biasing potential is 50 volts. The curves G and Grepresent a special case which will be described in a later part of thespecification.

It is clear from this family of curves that a Wide variation in thevalue of negative resistance, as determined by the slope of the fallingportion of the curves A, B, C, D, E, F, and G, may be obtained byaltering the value of the biasing potential, also that the operatingrange of the device, that isthe length of the falling portion of thecharacteristic is also controlled by the value of the bias. It should beunderstood that the characteristics represented in Fig. 10 were obtainedfrom a single tube of specific electrode dimensions, operating at adefinite filament temperature, and that each change in the diameter andspacing of the annular plates which comprise the negative resistanceelement 6 results in a different family of curves.

The operation of the device, is similar to that of my former U. S.Patent 2,002,238, granted May 21, 1935, in fact, when the biasingpotential represented by curves A and A between the groups of annularplates, 6a and 6b, is zero the operation is identical with the formerdevice. However, when a biasing potential is present the electrons aredeflected from their path toward the anode in the direction of thoseannular plates which are at the more positive potential, thus,increasing the desired effect, which is best described with reference toFigs. 6 and '7 When the electrons are moving slowly due to a relativelylow potential on the annular plate system 60., 6b, as a whole, withrespect to the cathode 3 all of the electrons emitted from the cathodeare precipitated upon the annular plates 60. and 6b by the action of thebiasing potential upon the electrons during their passage between theannular plates. This condition is clearly shown in Fig. 6. As thepotential of the annular plate system as a whole is increased, thebiasing potential remaining at some fixed value, the velocity of theelectrons in their passage between the annular plates increases and,hence, the time during which the biasing potential is effective indeflecting their motion toward the surfaces of the plates, becomes lessand less and an increasing number of electrons are enabled to passentirely through the spaces between the plates and, thus, reach theanode l2.

Eventually an upper limit is reached Where a minimum of electrons isreceived by the electrode 6 and a maximum number reach the anode. Thiscondition is depicted in Fig. '7.

Thus, over the working range of the device and as the potential ofelement 6 as a whole is increased, the current received by it decreases,providing the desired inverse current characteristic or negativeresistance.

The following mathematical analysis of this action yields a theoreticalexpression for the operating characteristics of the device which closelyapproximates those determined by experimental methods.

The primary assumption must be made that the rate of electron emissionfrom the cathode is constant over the operating range of potentialsapplied to electrode 6. Let this emission constant be represented by thesymbol A. Now even under the most favorable conditions for the passageof electrons through the openings of element 6 to the anode [2, shown inFig. 7, a portion of the electron stream is necessarily blocked by theelement 6 due to the thickness of the annular plates and support rodswhich comprise it, thus, causing a portion of the total current, A, to'fiow in the circuit of electrode 6 at all times. Let this'current berepresented by the symbol C which I shall call the blocking constant.

Now since the total current is a constant A the maximum current whichcan be received by the anode will be A minus C which I will represent bythe symbol K, which will hereinafter be referred to as the anodeconstant.

Now under operating conditions, the current received by electrode 6 willcomprise the constant C plus a portion of K. Thus the current i receivedby electrode 6 may be expressed by the relation i oK-l-C where 5 is afunction involving the accelerating potential, (that is, the eifectivepotential of electrode 6 as a Whole with respect to the cathode), thebiasing voltage between the two sets of annular plates 6a and 6b ofelectrode 6, and the geometrical dimensions of electrode 6. Theoperating range of the device is obviously limited to those conditionswhich produce values of between zero and unity.

Now, considering the combined efiects of the accelerating electrostaticfield which is parallel to the surfaces of the annular plates of element6 and the biasing field which is normal to the surfaces of the annularplates of element 6 upon the electron stream in its passage from thecathode toward the anodewe obtain the following expression for thecoefficient, qs.

where 1 represents the length of the radial path between the inner andouter edges of the annular plates of element 6.

d represents the spacing between the annular plates of element 6.

E represents the potential of the more positive of the two sets ofannular plates of element 6 with respect to the cathode.

e represents the biasing potential between the two sets of annularplates of element 6, e being always in the negative direction withrespect to E, so that the accelerating potential, that is, the averagepotential of element 6 as a whole with respect to the cathode becomesThus, the expression for the current received by element 6 becomes =dE=n) It is clear from these relations that when the form of the element 6and the emission rate remain 'constant a family of curves is obtainedfor various values of e in which the current i varies inversely with thepotential E within the working range of the device, similar inform tothe curves shown in Fig. 10, when practical values are chosen for theconstants K and C.

In the development of this expression I have assumed the emission to beconstant for all values of E. However, in practice, it is not possibleto obtain this ideal condition, and in the form of the device shown inFig. 1, I have employed a tungsten filament which, due to the well knownphenomenon of saturation, produces a substan tially constant rate ofelectron emission above a certain critical field strength at the cathodesurface. Thus, the lower limit of the useful working range of the deviceis established by that value of potential which causes a field strengthat the cathode just sufiicient to produce saturation.

It should also be noted that when the biasing potential 6 is zero, theabove theoretical relation shows the current i to be a constant for allvalues of E, whereas, experimentally, an inverse curve results as shownin Fig. 10, curve A. This is due to the fact that the, electronscomprising the stream flowing between the annular plates constitute aspace charge equivalent in its action to a small biasing potential whichcauses the electrons to spread towards the annular plates in the mannerdescribed in my former Patent No. 2,002,238, granted May 21, 1935.

The accelerating potential has been considered as being equal to theaverage potential of the two sets of annular plates comprising electrode6, that is, one set has the potential E with respect to the cathode andthe other, (E-e) thus making the average equivalent to Now forrelatively large values of e this condition not substantially parallelto the surfaces of the annular plates comprising element 6, thusincreasing the value of the blocking constant C and reducing theefficiency of the device.

This defect is of importance only in the larger power tubes whererelatively high values of both e and d are employed to obtain thedesired characteristics. In such cases I have overcome this difficultyby increasing the spacing between the cathode and the inner edges of themore positive set of annular plates of electrode 6, so that thepotential gradient between the cathode and each set of annular platescomprising element 6 is the same at the upper limit of the operatingrange of the device, thus imparting an equal acceleration to allelectrons leaving the cathode in a direction which is substantiallyparallel to the surfaces of all the annular plates of element 6 at theupper limit of E, where it is desired that element 6 shall receive aminimum of current.

An important use of my device is as a genertube by limiting thealternating voltage applied to the electrodes, and making for a highdegree of frequency stability which is important in many applications.

The operation of the device in this circuit arrangement is as follows:The filament or cathode 3 is heated to incandescence by means of thebattery 24. The biasing battery 25 is connected between the two sets ofannular plates 6a and 6b which together comp-rise the negativeresistance element 6. The battery 25 is connected so that the set ofannular plates 5a is negative with respect to the other set 61). Thenegative resistance element 6 is connected to the inductance 2| at apoint 21 such that the portion of the parallel resonant circuit includedin the circuit of element 6 presents a load, or effective positiveresistance, slightly greater in value than the value of the negativeresistance generated in this circuit by virtue of the inverse currentcharacteristic of element 6.

When I refer to negative resistance, I have reference to the slope ofthe current-voltage relationship, and when this slope is negative, poweris delivered to a circuit including the negative resistance, and thesmaller the numerical value of the negative resistance, the more poweris delivered to the circuit. If the value or" the negative resistance isinfinite, it delivers no power to the circuit.

The term negative resistance as used in the specification means thenumerical value of the ratio (as d1 which is the reciprocal of the slopeof the current voltage curve, it is negative if cLu'rent increases whenvoltage is decreased, and the steeper the negative slope, the smallerthe value of negative resistance, and to maintain oscillation in aparallel resonant circuit, the numerical value of negative resistancemust be smaller than the numeri-, cal value of the equivalent parallelresistance of the resonant circuit. In former devices it has not beenpossible to obtain such long steep negative slopes to current voltagecurves, that is, such low numerical values of negative resistance.

The lower end of the parallel resonant circuit is connected to a tap onthe battery 26 so' that the element 6 as a whole is maintained at asuitable positive potential with respect to the cathode 3. The anode I2is maintained at a higher positive potential with respect to the cathodeby being connected so as to include the entire battery 26.

Under these conditions oscillations will be generated in the resonantcircuit 20 at a frequency determined substantially by the constants ofthis circuit, because of the well known action of nega-' tiveresistance. That is, if the negative resistance device delivers slightlymore power to the resonant circuit per cycle than is lost throughradia-. tion and heating, oscillations will build up to an equilibriumlevel and continue as long as the proper conditions are maintained.

Since my device is capable of generating rela tively low values ofnegative resistance, when it is connected to a parallel resonant circuitof eificient design, that is, one having low losses, the portion of theinductance 2| which is included in the negative resistance circuit maybe as low as or percent of the total inductance. Under these conditionsthe frequency generated by the system is determined by the constants ofthe resonant circuit alone, capacity and other effects of the negativeresistance device which might influence the frequency, being reduced toa minimum; by virtue of the small percentage of the resonant circuitincluded in the negative resistance circuit.

Thus, my device provides an ideal means for generating electricaloscillations where a high degree of frequency stability is required.

Referring now to Fig; 9, in this figure I show a schematic diagram of acircuit in which my device may serve either as an amplifier or as agenerator of alternating currents. In this case a relatively high degreeof efliciency obtains, and power in the form of pulsating or alternatingcurrents is produced in the anode circuit from which it may be conductedby means of conventional coupling 3! to an antenna or other useful workcircuit.

The operation of the device in the circuit shown in Fig. 9 is asfollows: The filament 3 is heated to incandescence by means of thebattery 24, one set of annular plates 6b is connected to a point 21 onthe inductance 2!, the other set of annular plates to is connected tothe point higher on the inductance. The bias voltage between Ga and 6bis obtained by means of the resistor 28 which is connected in serieswith the lead from 6a to the point 38 on the inductance. As has beenpointed out some of the electrons emitted from the cathode must alwaysstrike the annular plates due to their thickness and this currentflowing through the resistance 28 causes the potential of 6a to becomelower than that of 62), thus, providing the desired bias. The value ofthe bias may easily be varied by changing the value of the resistance28. The condenser 29 is connected in parallel with the resistance 28 toprovide a path for the alternating currents which must, flow to theplates Get. It will be understood that a battery as shown in Fig. 8 maybe employed in lieu of the resistor 28 and condenser 29.

As before, the lower end of the parallel resonant circuit 20 isconnected to a portion of the battery 26 so that the element 6 ismaintained at a positive potential with respect to the cathode. Theanode I2 is maintained at a higher positive potential with respect tothe cathode by being connected so as to include the entire battery 26.The output coupling element 3| is connected in series with the anodelead to provide a convenient means for conveying the power generated inthe system to a work circuit such as an antenna.

In the operation of the device under these conditions, the leadconnected to the point 21 on the inductance 21 carries the major portionof the inverse current since 6b is the more positive set of annularplates and, hence, the point 21 is chosen soas to obtain the propermatching of positive and negative resistance as described above. Themore negative set of annular plates to being connected to a point higheron the inductance 2| receives a higher alternating current potentialthan 61) when oscillations occur in the resonant circuit 20. The effectof this arrangement is to increase the bias when the variable componentof voltage swings below the working voltage, and to decrease the biascorrespondingly when the variable component swings above the workingvoltage. For example, referring again to Fig. 10, if we select a workingvoltage of E0 and a fixed bias such that the static curve F is producedwe obtain a dynamic characteristic designated at G and G when thevariable component at the point 21 swings above and below the workingvoltage E by the amount it.

Thus the more positive set of annular plates 6b will move through arange of potentials (Eo+a sin wt) and the other set 6a will move througha wider range where n represents the coupling ratio between the twopoints 27 and 30 on the inductance 2| of Fig. 9. This action isequivalent to progressively increasing the bias potential e as thevariable component swings below E0 and progressively decreasing the biasas it swings above Eb, thus producing the steeper inverse currentcharacteristic G, in Fig. 10 and causing the maximum current variationsto occur in the anode circuit corresponding to the curve G in Fig. 10.In the development of curve G the coupling ratio of 2 was used, that is,n=2. That is: the variable component of voltage at 21, Fig. 9, is a sinwt; and at 30, it is: 2a sin wt.

The following approximate theoretical expression for this dynamiccharacteristic G has been derived from the basic current potentialrelation previously developed.

It will be noted that the curve G in Fig. 10 represents a negativeresistance of extremely low value. In actual practice, I have producednegative resistance conditions lower in value than could be produced bypreviously known negative resistance devices of similar physical andelectrical dimensions.

Where it is desired to employ my device as an amplifier rather than asan oscillator, it is only necessary to adjust the resistance 28 of Fig.9 to a value such that the negative resistance generated is slightlygreater than that required to produce oscillations and apply theimpulses to be amplified to the point 21 by coupling with the inductance2|, for example. Where amplification rather than oscillation is desired,it may be advantageous to eliminate the condenser 23 employing only thetapped inductance 2| in the circuit associated with element 6.

It will be understood that the oscillatory systems of my inventionfunction through the action of negative resistance and do not depend Ihave found the method of operation, construction and arrangement of thenegative resistance of my invention highly practical. I realize thatmodifications and changes may be made in the construction andarrangement of parts of the device and the circuit in which the deviceis connected, and I accordingly intend no limitations upon my inventionother than may be imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is as follows:

1. The method of producing negative resistance which includes theprojection of a constant current electron stream, and the maintenance ofa substantially constant transverse electrostatic field and of alongitudinal electrostatic field subject to variation, the transversecomponent of current in the electron stream being inversely variablewith the strength of the longitudinal electrostatic field.

2. The method of producing negative resistance which includes theprojection of a constant current electron stream, the maintenance of alongitudinal and of a transverse electrostatic field for affecting theelectrons in the electron stream, and the variation of the strength ofthe longitudinal electrostatic field for varying the velocity ofelectrons in the stream and permitting the transverse electrostaticfield to influence the electrons in correspondingly varying degree.

3. A negative resistance device, comprising an evacuated vessel, anelectron emitting cathode and an anode therein, a negative resistanceelement disposed between said electron emitting cathode and said anodeand comprising a multiplicity of spaced parallel disposed plates, meansincluding said cathode for producing a constant flow of electrons fromthe cathode toward said anode in a direction parallel to said plates,means for applying an accelerating potential to said element as a whole,said accelerating potential being subject to variation for varying thevelocity of electronsfiowlng from said cathode to said plate, and meansfor establishing substantially constant electrostatic deflecting fieldsbetween said plates normal-to the path of said electrons, whereby theportion of the electron stream received by the negative resistanceelement varies inversely with the said accelerating potential appliedthereto as a whole.

4. A negative resistance device, comprising an evacuated envelope, anelectron emitting cathode, means including said cathode for producing -aconstant current electron stream, an anode interposed in the path ofsaid stream, means for maintaining said anode at a positive potentialwith respect to said cathode, and a negative resistance element disposedbetween said anode and said cathode, means for maintaining said elementat a less positive potential than said anode with respect to saidcathode for producing an electrostatic accelerating field in thedirection of said electron stream, said element comprising a pluralityof parallel spacially related plates forming a geometrical figure whoselateral extension as compared with the spacial relation of the platemembers is such that electrostatic lines of force between said platesand said cathode, and between said plates and said anode, extend onlypartly into the space between the plates comprising the negativeresistance element, and. wherein no lines of electrostatic force extendbetween the plates from said. cathode to said anode, the potential ofsaid element with respect to said cathode being subject to variation forvarymg the velocity of electrons passing between said plates to saidanode, and means for establishing a substantially constant difference ofpotential between consecutive plates of the negative resistance elementfor producing a constant electrostatic deflecting field normal to thedirection of said electron stream whereby the quantity of electronsreceived by the said negative resistance element from said cathodevaries inversely with electron emitting cathode, means including saidcathode for producing'a constant current electron stream, an anode, anda negative resistance element disposed therebetween means formaintaining said anode at a positive potential with respect to the saidcathode, and the said negative resistance element comprising a pluralityof spaced parallel plates so oriented as to oiTer a minimum ofobstruction to the rectilinear passage of electrons from said cathode tosaid anode, said negative resistance element being connected to twodiiferent sources of potential, a variable primary potential from afirst of said sources adapted to maintain the element as a wholepositive with respect to said cathode, and a substantially constantsecondary potential from the other of said sources adapted to maintain adifierence of potential between consecutive plates of said negativeresistance element, said element having an inverse currentcharacteristic over a useful working range with respect to the primaryvoltage applied to it substantially of the form wherein E=the variableprimary or accelerating potential of the negative resistance elementwith respect to said cathode; e=the constant secondary potential whoseelectrostatic field is normal to that of the accelerating potential E;Z=length of the path between the plates; d=distance between the plates;K=the constant representing the maximum current which may be received bythe anode; and C=blocking constant depending upon obstruction toelectrons ofiered by the plates of said negative resistance element.

6. In a high frequency oscillatory system a negative resistance devicecomprising an evacuated vessel including an electron emitting cathodefor supplying a constant current of electrons, an anode, and a negativeresistance element disposed therebetween, said negative resistanceelement including sets of plate members, one set of said plate membersbeing alternately interposed in spacial relation between the other setof said plate members, means for establishing a difference of potentialbetween consecutive plate members, a source of voltage connected betweensaid cathode and anode, and a resonant circuit connected between saidnegative resistance element and an intermediate point on said source ofvoltage.

'7. In a high frequency oscillatory system, a negative resistance devicecomprising an evacuated vessel including an electron emitting cathodefor supplying a constant current of electrons, an anode, and a negativeresistance element disposed therebetween, said negative resistanceelement including sets of plate members, one set of said plate membersbeing alternately interposed in spacial relation between the other setof said plate members, means for establishing a difference of potentialbetween consecutive plate members, a source of potential connectedbetween said cathode and anode, a resonant circuit including aninductance element, a connection from one side of said resonant circuitto an intermediate point on said source of potential, and a connectionfrom said negative resistance element to a tap on said inductance, thelocation of said tap on said inductance being selected so that theeffective positive resistance presented by the resonant circuit issubstantially balanced by the negative resistance provided by saiddevice.

8. In a high frequency oscillatory system, a negative resistance devicecomprising an evacuated vessel including an electron emitting cathodefor supplying a constant current of electrons, an anode, and a negativeresistance element disposed therebetween and comprising interleaved setsof plate members, means for establishing a difference of potentialbetween the respective sets of plate members, a source of voltageconnected between said cathode and anode, a resonant circuit includinginductance, capacity and resistance elements, taps on said inductanceindividually connected with the respective sets of said plate members,the tap of higher dynamic potential being connected with the set oflower static potential, and a connection between said resonant circuitand an intermediate point on said source of voltage.

9. In a high frequency oscillatory system, a negative resistance devicecomprising an evacuated vessel including an electron emitting cathodefor supplying a constant current of electrons, an anode, and a negativeresistance element disposed therebetween and comprising interleaved setsof plate members, a source of voltage connected between said cathode andanode, a resonant circuit including inductance, capacity and resistanceelements, a connection between a tap on said inductance and one of saidsets of plate members, a connection between a tap of higher oscillatorypotential on said inductance and the other of said sets of platemembers, whereby different values of said inductance are included in theconnections to said sets of plate members, means included in the secondsaid connection for deriving a bias potential for the respective set ofplate members relative to the other of said sets, and a connectionbetween said resonant circuit and an intermediate point on said voltagesource.

10. A negative resistance device including a cathode structure forproducing a constant current electron stream, an anode structureinterposed in the path of said stream, a negative resistance element,means including said element for producing a variable electrostaticaccelerating field in the direction of said stream, and means alsoincluding said element for producing a constant electrostatic deflectingfield normal to the direction of said electron stream.

11. The method of producing negative resistance as set forth in claim 2and including further the progressive increasing in strength of thetransverse electrostatic field as the strength of the longitudinalelectrostatic field decreases, and vice versa, for producing negativeresistance of increased value.

12. In a negative resistance device as set forth in claim 10, anarrangement for accentuating the negative resistance characteristic ofthe negative resistance element comprising in combination with the meansfor producing a variable accelerating field, means for varying thedeflecting field inversely and in proportion to the variation of theaccelerating field.

13. A negative resistance electron tube device comprising a cathodestructure, means including said cathode structure for producing aconstant current electron stream, an anode structure interposed in thepath of said stream, a negative resistance element comprising a pair ofplate members disposed parallel with respect to the electron stream insaid device, means for applying an operating potential to said elementas a whole with respect to said cathode structure, means for applying abias voltage between the plate members comprising said element, andmeans for subjecting the operating potential applied to said element asa whole to variations for thereby affecting the velocity of electrons insaid electron stream, the number of electrons received by said elementbeing in inverse relation to the velocity of the electrons in thestream, as determinedby the potential of said element as a Whole, and indirect relation to the biasing voltage between said plate members,Within the working range of the device.

EDWARD H. YONKERS, JR.

